Mechanism of action
- Opioid analgesic (weak)
- Analgesic properties are based mostly on its selective agonism to the μ-opioid receptor (MOR) which is crucial for transmission of information about pain throughout the central nervous system. These receptors are located mostly in brainstem and thalamus.
- Directly supresses cough and respiratory centres in the medulla.
- Small portion of codeine is converted directly to morphine and works as such.
Indications and dose
Pharmacokinetics
Onset of action: 30–45 minutes
Duration of action: 4 hours
Half-life of elimination: 3–4 hours
Metabolism: Hepatic
Elimination: Kidneys
Directions for administration
Lowest effective dose for shortest time possible is recommended when using as an analgesic.
Combination with non-opioid analgesics (paracetamol) significantly increases the analgesic effect of codeine.
Medicinal forms
Pills – 15 mg, 30 mg
Side-effects
Prolonged use as painkiller for headache may make the pain worse
Drowsiness
Nausea, vomiting
Confusion
Tolerance, addiction
Tachycardia, bradycardia, palpitations
Postural hypotension
Mental depression
Anorexia
Constipation
Dry mouth
Pancreatitis
Dyspnoea
Respiratory depression
References
